In various industries driverless vehicles are loaded with heavy loads and move along a guide path that has one or more inclined portions. For example, in the printing industry rolls of paper weighing several tons are conveyed by vehicles from a storage area to a printing area. If a portion of the floor is inclined, the vehicle carrying a heavy load will be propelled by gravity so as to generate sufficient kinetic energy whereby damage will be caused when the vehicle collides with some other object.
The problem solved is how to retard fast moving driverless vehicles moving under the effect of gravity with a heavy load on an inclined floor while not significantly effecting the velocity of slow moving empty vehicles.